1. Field of the Invention
This invention is related to multimedia systems and, more particularly, to a palette for supporting multiple extended modes of video data for display.
2. Description of Related Art
The capability of displaying full-color, 32-bit images on high-resolution monitors has, in recent years, become increasingly in demand, particularly in multimedia and scientific visualization applications. However, full-color, 32-bit images require enormous amounts of storage space which, in turn, increases the cost of such imaging systems considerably. For example, a single full-color, 32-bit image on a high resolution display can often require as much as 3-4 Mbytes of data. In contrast, a single gray-scale image typically requires 1 Mbytes of data and a single black-and-white image typically requires only 125 Kbytes of data. These storage requirements are particularly problematic in animated graphic and/or full motion video applications. Animated graphic applications require the storage and display of hundreds of screen images in sequence. Full-motion color video applications, on the other hand, requires the display of 30 frames, each demanding approximately 1 Mbyte of storage space, per second. Thus, one minute of full motion color video will require a storage capacity of almost 2 Gigabytes.
Even assuming that sufficient storage capacity is available, data transfer rates pose yet another obstacle to widespread use of full color video imaging systems. Most desktop computers fall well short of the 30 Mbps data transfer rate required for full-motion color video applications. For example, the hard disk drives commonly found in many desktop computers have data transfer rates of 1 to 2 MBps. Furthermore, the data buses most commonly associated with such computer systems also tend to transfer data at rates under 20 MBps. For example, the AT bus drive runs at 8 MBps.
The CD has long been viewed as the solution to the storage requirements for full-motion color video applications. CD-ROM drives, however, tend to transfer data at rates slower than hard disk drives. Thus, while the much larger storage space of the CD is capable of addressing one problem with full-motion color video applications, the relatively slow CD-ROM drive remains an obstacle.
The solution to these problems is the use of data compression to reduce the size of the data required to represent a graphic image. The basic component of an image is the pixel and most image compression techniques address the visual attributes (color and transparency) attached to each pixel of an image. Because images generally have regions of uniform color or pattern, most commonly in the background, it is possible to represent the visual attributes of these regions using much less data information than that required to separately represent each individual pixel in that region. For this reason, many image compression schemes such as those disclosed in U.S. Pat. Nos. 4,785,349 to Keith et al and 4,868,653 to Golin et al. are directed towards dividing an image into various regions for individually encoding the visual attributes of the regions. Other methods such as those disclosed in U.S. Pat. Nos. 4,953,196 to Ishikawa et al. and 5,300,377 to Lipmann et al. exploit the fact that certain components of the data information for an image are less important than the data information of other components of the image.
The demands on the multimedia system to support the display of various types of images varies from image to image. For example, the demands on the multimedia system needed to support animated graphic applications vary dramatically from that of full-motion color video. Accordingly, to increase the efficiency and versatility of multimedia systems to perform the many applications of which such system are capable, it has been desired to configure the multimedia system to readily support the display of images in multiple modes.